We propose, analyze, and evaluate a technique for the joint measurement of time–frequency entanglement between two photons. In particular, we show that the frequency sum and time difference of two photons could be simultaneously measured through the sum-frequency generation process, without measuring the time or frequency of each individual photon. We demonstrate the usefulness of this technique by using it to design a time–frequency entanglement based continuous variable superdense coding and a quantum illumination protocol. Performance analysis of these two protocols suggests that the joint measurement of strong time–frequency entanglement of non-classical photon pairs can significantly enhance the performance of joint-measurement based quantum communication and metrology protocols.

我们提出，分析和评估一种技术，用于联合测量两个光子之间的时频纠缠。特别地，我们表明可以通过和频生成过程同时测量两个光子的频率和和时差，而无需测量每个单独的光子的时间或频率。通过使用该技术设计基于时频纠缠的连续变量超密编码和量子照明协议，我们证明了该技术的实用性。对这两种协议的性能分析表明，非经典光子对的强时频纠缠联合测量可以显着提高基于联合测量的量子通信和计量协议的性能。